| <!DOCTYPE html> |
| <html lang="en"> |
| <head> |
| <meta charset="utf-8"> |
| <meta name="viewport" content="width=device-width,initial-scale=1.0"> |
| <title>Guarantees | Apache Cassandra Documentation</title> |
| <link rel="stylesheet" href="../../../../assets/css/site.css"> |
| <link rel="schema.dcterms" href="https://purl.org/dc/terms/"> |
| <meta name="dcterms.subject" content="Cassandra"> |
| <meta name="dcterms.identifier" content="4.0"> |
| <meta name="generator" content="Antora 2.3.4"> |
| <link rel="icon" href="../../../../assets/img/favicon.ico" type="image/x-icon"> |
| <script> |
| const script = document.createElement("script"); |
| const domain = window.location.hostname; |
| script.type = "text/javascript"; |
| script.src = "https://plausible.cassandra.apache.org/js/plausible.js"; |
| script.setAttribute("data-domain",domain); |
| script.setAttribute("defer",'true'); |
| script.setAttribute("async",'true'); |
| document.getElementsByTagName("head")[0].appendChild(script); |
| </script> </head> |
| <body class="docs-wrapper article"> |
| <div class="container mx-auto relative"> |
| <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script> |
| <meta property="og:type" content="website" /> |
| <meta property="og:url" content="/" /> |
| <meta property="og:site_name" content="Apache Cassandra" /> |
| |
| <header id="top-nav"> |
| <div class="inner relative"> |
| <div class="header-social-icons text-right"> |
| <a href="https://twitter.com/cassandra?lang=en" target="_blank" styles="margin-left: 20px;"><img src="../../../../assets/img/twitter-icon-circle-white.svg" alt="twitter icon" width="24"></a> |
| <a href="https://www.linkedin.com/company/apache-cassandra/" target="_blank" styles="margin-left: 20px;"><img src="../../../../assets/img/LI-In-Bug.png" alt="linked-in icon" width="24"></a> |
| <a href="https://www.youtube.com/c/PlanetCassandra" target="_blank" styles="margin-left: 20px;"><img src="../../../../assets/img/youtube-icon.png" alt="youtube icon" width="24"></a> |
| </div> |
| <div class="cf"> |
| <div class="logo left"><a href="/"><img src="../../../../assets/img/logo-white-r.png" alt="Cassandra Logo"></a></div> |
| <div class="mobile-nav-icon right"> |
| <img class="toggle-icon" src="../../../../assets/img/hamburger-nav.svg"> |
| </div> |
| <ul class="main-nav nav-links right flex flex-vert-center flex-space-between"> |
| <li> |
| <a class="nav-link hide-mobile">Get Started</a> |
| <ul class="sub-menu bg-white"> |
| <li class="pa-micro"> |
| <a href="/_/cassandra-basics.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-basics.png" alt="cassandra basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Cassandra Basics |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/quickstart.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-rocket.png" alt="cassandra basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Quickstart |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/ecosystem.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-ecosystem.png" alt="cassandra basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Ecosystem |
| </div> |
| </a> |
| </li> |
| </ul> |
| </li> |
| <li><a class="nav-link" href="/doc/latest/">Documentation</a></li> |
| <li> |
| <a class="nav-link" href="/_/community.html">Community</a> |
| <ul class="sub-menu bg-white"> |
| <li class="pa-micro"> |
| <a href="/_/community.html#code-of-conduct"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-welcome.png" alt="welcome icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Welcome |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#discussions"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-discussions.png" alt="discussions icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Discussions |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#project-governance"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-governance.png" alt="Governance icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Governance |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#how-to-contribute"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-contribute.png" alt="Contribute icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Contribute |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/community.html#meet-the-community"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-community.png" alt="Meet the Community icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Meet the Community |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/cassandra-catalyst-program.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-catalyst.png" alt="Catalyst icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Catalyst Program |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro hide-mobile"> |
| <a href="/_/events.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-events.png" alt="Events icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Events |
| </div> |
| </a> |
| </li> |
| </ul> |
| </li> |
| <li> |
| <a class="nav-link hide-mobile">Learn</a> |
| <ul class="sub-menu bg-white"> |
| <li class="pa-micro"> |
| <a href="/_/Apache-Cassandra-5.0-Moving-Toward-an-AI-Driven-Future.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-basics.png" alt="Basics icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Cassandra 5.0 |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/case-studies.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-case-study.png" alt="Case Studies icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Case Studies |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/resources.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-resources.png" alt="Resources icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Resources |
| </div> |
| </a> |
| </li> |
| <li class="pa-micro"> |
| <a href="/_/blog.html"> |
| <div class="sub-nav-icon"> |
| <img src="../../../../assets/img/sub-menu-blog.png" alt="Blog icon"> |
| </div> |
| <div class="sub-nav-text teal py-small"> |
| Blog |
| </div> |
| </a> |
| </li> |
| </ul> |
| </li> |
| <li><a class="nav-link btn btn--filled" href="/_/download.html">Download Now</a></li> |
| </ul> |
| </div> |
| </div> |
| </header> |
| |
| <div class="hero hero--home grad"> |
| <div class="eye"></div> |
| <div id="docs-content" class="text-center flex flex-center flex-column relative z2 ma-xlarge"> |
| <h2>Cassandra Documentation</h2> |
| </div> |
| </div> |
| <div class="body px-medium py-medium container"> |
| <div class="docs-nav-bar flex flex-space-between mb-medium"> |
| <div id="mobile-docs-nav-burger" class="hidden"> |
| <svg viewBox="0 0 24 24" width="36" height="36" stroke="#1c81a0" stroke-width="2.5" fill="none" stroke-linecap="round" stroke-linejoin="round" class="css-i6dzq1"><line x1="3" y1="12" x2="21" y2="12"></line><line x1="3" y1="6" x2="21" y2="6"></line><line x1="3" y1="18" x2="21" y2="18"></line></svg> |
| </div> |
| <div class="docs-nav-item relative"> |
| <input id="search-input" type="text" placeholder="Search docs"> |
| </div> |
| <div class="versions-wrapper"> |
| <h4>Version:</h4> |
| <div class="nav-panel-explore" data-panel="explore"> |
| |
| <div id="version-toggle" class="context"> |
| <span class="version">4.0</span> |
| </div> |
| <ul id="versions-list" class="components"> |
| <li class="component"> |
| <ul class="versions"> |
| <li class="version is-latest"> |
| <a href="../../../../_/index.html">master</a> |
| </li> |
| </ul> |
| </li> |
| <li class="component is-current"> |
| <ul class="versions"> |
| <li class="version"> |
| <a href="../../../trunk/index.html">trunk</a> |
| </li> |
| <li class="version"> |
| <a href="../../../5.0/index.html">5.0</a> |
| </li> |
| <li class="version is-latest"> |
| <a href="../../../4.1/index.html">4.1</a> |
| </li> |
| <li class="version is-current"> |
| <a href="../../index.html">4.0</a> |
| </li> |
| <li class="version"> |
| <a href="../../../3.11/index.html">3.11</a> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| </div> </div> |
| <div class="cf relative"> |
| <nav class="nav docs-nav full-800"> |
| <div class="nav-menu"> |
| <ul class="nav-list"> |
| <li class="nav-item is-active" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="1"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../index.html">Main</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/glossary.html">Glossary</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/bugs.html">How to report bugs</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/contactus.html">Contact us</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item is-active" data-depth="0"> |
| <ul class="nav-list"> |
| <li class="nav-item is-current-path is-active" data-depth="1"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <span class="nav-text">Cassandra</span> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../getting_started/index.html">Getting Started</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../getting_started/installing.html">Installing Cassandra</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../getting_started/configuring.html">Configuring Cassandra</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../getting_started/querying.html">Inserting and querying</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../getting_started/drivers.html">Client drivers</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../getting_started/production.html">Production recommendations</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../new/index.html">What’s new</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/java11.html">Support for Java 11</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/virtualtables.html">Virtual tables</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/auditlogging.html">Audit logging</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/fqllogging.html">Full query logging</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/messaging.html">Improved internode Messaging</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/streaming.html">Improved streaming</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../new/transientreplication.html">Transient replication</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item is-current-path is-active" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="index.html">Architecture</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="overview.html">Overview</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="dynamo.html">Dynamo</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="storage_engine.html">Storage engine</a> |
| </span> |
| </li> |
| <li class="nav-item is-current-page is-active" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="guarantees.html">Guarantees</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../data_modeling/index.html">Data modeling</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/intro.html">Introduction</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_conceptual.html">Conceptual data modeling</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_rdbms.html">RDBMS design</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_queries.html">Defining application queries</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_logical.html">Logical data modeling</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_physical.html">Physical data modeling</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_refining.html">Evaluating and refining data models</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_schema.html">Defining database schema</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../data_modeling/data_modeling_tools.html">Cassandra data modeling tools</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../cql/index.html">Cassandra Query Language (CQL)</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/definitions.html">Definitions</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/types.html">Data types</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/ddl.html">Data definition (DDL)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/dml.html">Data manipulation (DML)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/operators.html">Operators</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/indexes.html">Secondary indexes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/mvs.html">Materialized views</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/functions.html">Functions</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/json.html">JSON</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/security.html">Security</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/triggers.html">Triggers</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/appendices.html">Appendices</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/changes.html">Changes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/SASI.html">SASI</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../cql/cql_singlefile.html">Single file of CQL information</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../configuration/index.html">Configuration</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_yaml_file.html">cassandra.yaml</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_rackdc_file.html">cassandra-rackdc.properties</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_env_sh_file.html">cassandra-env.sh</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_topo_file.html">cassandra-topologies.properties</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_cl_archive_file.html">commitlog-archiving.properties</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_logback_xml_file.html">logback.xml</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../configuration/cass_jvm_options_file.html">jvm-* files</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../operating/index.html">Operating</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="#operating/snitch.adoc">Snitches</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/topo_changes.html">Topology changes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/repair.html">Repair</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/read_repair.html">Read repair</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/hints.html">Hints</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/bloom_filters.html">Bloom filters</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/compression.html">Compression</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/cdc.html">Change Data Capture (CDC)</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/backups.html">Backups</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/bulk_loading.html">Bulk loading</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/metrics.html">Metrics</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/security.html">Security</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/hardware.html">Hardware</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/audit_logging.html">Audit logging</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../operating/compaction/index.html">Compaction</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../tools/index.html">Tools</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../tools/cqlsh.html">cqlsh: the CQL shell</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../tools/nodetool/nodetool.html">nodetool</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../tools/sstable/index.html">SSTable tools</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../tools/cassandra_stress.html">cassandra-stress</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../troubleshooting/index.html">Troubleshooting</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../troubleshooting/finding_nodes.html">Finding misbehaving nodes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../troubleshooting/reading_logs.html">Reading Cassandra logs</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../troubleshooting/use_nodetool.html">Using nodetool</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../troubleshooting/use_tools.html">Using external tools to deep-dive</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <button class="nav-toggle"></button> |
| <a class="nav-link" href="../../../../_/development/index.html">Development</a> |
| </span> |
| <ul class="nav-list"> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/gettingstarted.html">Getting started</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/ide.html">Building and IDE integration</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/testing.html">Testing</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/patches.html">Contributing code changes</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/code_style.html">Code style</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/how_to_review.html">Review checklist</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/how_to_commit.html">How to commit</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/documentation.html">Working on documentation</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/ci.html">Jenkins CI environment</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/dependencies.html">Dependency management</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="3"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../../../../_/development/release_process.html">Release process</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../faq/index.html">FAQ</a> |
| </span> |
| </li> |
| <li class="nav-item" data-depth="2"> |
| <span class="nav-line"> |
| <a class="nav-link" href="../plugins/index.html">Plug-ins</a> |
| </span> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| </nav> |
| <aside class="toc sidebar"> |
| <div class="toc-menu"></div> |
| </aside> |
| <main class="article default-main full-800" data-ceiling="topbar"> |
| <div class="article-banner"> |
| <p>A newer version of this documentation is available.</p> |
| <a class="btn" href="../../../4.1/cassandra/architecture/guarantees.html">View Latest</a> |
| </div> |
| <div class="article-header"> |
| <nav class="crumbs" aria-label="breadcrumbs"> |
| <ul> |
| <li class="crumb">Cassandra</li> |
| <li class="crumb"><a href="index.html">Architecture</a></li> |
| <li class="crumb"><a href="guarantees.html">Guarantees</a></li> |
| </ul> |
| </nav> |
| <div class="tools" role="navigation"> |
| <ul> |
| <li class="tool edit"><a href="https://github.com/apache/cassandra/edit/cassandra-4.0/doc/modules/cassandra/pages/architecture/guarantees.adoc" title="Edit Page" target="_blank" rel="noopener">Edit</a></li> |
| </ul> |
| </div> |
| </div> |
| <article class="doc"> |
| <h1 class="page">Guarantees</h1> |
| <div id="preamble"> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Apache Cassandra is a highly scalable and reliable database. Cassandra |
| is used in web based applications that serve large number of clients and |
| the quantity of data processed is web-scale (Petabyte) large. Cassandra |
| makes some guarantees about its scalability, availability and |
| reliability. To fully understand the inherent limitations of a storage |
| system in an environment in which a certain level of network partition |
| failure is to be expected and taken into account when designing the |
| system it is important to first briefly introduce the CAP theorem.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="what-is-cap"><a class="anchor" href="#what-is-cap"></a>What is CAP?</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>According to the CAP theorem it is not possible for a distributed data |
| store to provide more than two of the following guarantees |
| simultaneously.</p> |
| </div> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p>Consistency: Consistency implies that every read receives the most |
| recent write or errors out</p> |
| </li> |
| <li> |
| <p>Availability: Availability implies that every request receives a |
| response. It is not guaranteed that the response contains the most |
| recent write or data.</p> |
| </li> |
| <li> |
| <p>Partition tolerance: Partition tolerance refers to the tolerance of a |
| storage system to failure of a network partition. Even if some of the |
| messages are dropped or delayed the system continues to operate.</p> |
| </li> |
| </ul> |
| </div> |
| <div class="paragraph"> |
| <p>CAP theorem implies that when using a network partition, with the |
| inherent risk of partition failure, one has to choose between |
| consistency and availability and both cannot be guaranteed at the same |
| time. CAP theorem is illustrated in Figure 1.</p> |
| </div> |
| <div class="imageblock"> |
| <div class="content"> |
| <img src="../_images/Figure_1_guarantees.jpg" alt="image"> |
| </div> |
| </div> |
| <div class="paragraph"> |
| <p>Figure 1. CAP Theorem</p> |
| </div> |
| <div class="paragraph"> |
| <p>High availability is a priority in web based applications and to this |
| objective Cassandra chooses Availability and Partition Tolerance from |
| the CAP guarantees, compromising on data Consistency to some extent.</p> |
| </div> |
| <div class="paragraph"> |
| <p>Cassandra makes the following guarantees.</p> |
| </div> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p>High Scalability</p> |
| </li> |
| <li> |
| <p>High Availability</p> |
| </li> |
| <li> |
| <p>Durability</p> |
| </li> |
| <li> |
| <p>Eventual Consistency of writes to a single table</p> |
| </li> |
| <li> |
| <p>Lightweight transactions with linearizable consistency</p> |
| </li> |
| <li> |
| <p>Batched writes across multiple tables are guaranteed to succeed |
| completely or not at all</p> |
| </li> |
| <li> |
| <p>Secondary indexes are guaranteed to be consistent with their local |
| replicas data</p> |
| </li> |
| </ul> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="high-scalability"><a class="anchor" href="#high-scalability"></a>High Scalability</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Cassandra is a highly scalable storage system in which nodes may be |
| added/removed as needed. Using gossip-based protocol a unified and |
| consistent membership list is kept at each node.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="high-availability"><a class="anchor" href="#high-availability"></a>High Availability</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Cassandra guarantees high availability of data by implementing a |
| fault-tolerant storage system. Failure detection in a node is detected |
| using a gossip-based protocol.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="durability"><a class="anchor" href="#durability"></a>Durability</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Cassandra guarantees data durability by using replicas. Replicas are |
| multiple copies of a data stored on different nodes in a cluster. In a |
| multi-datacenter environment the replicas may be stored on different |
| datacenters. If one replica is lost due to unrecoverable node/datacenter |
| failure the data is not completely lost as replicas are still available.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="eventual-consistency"><a class="anchor" href="#eventual-consistency"></a>Eventual Consistency</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Meeting the requirements of performance, reliability, scalability and |
| high availability in production Cassandra is an eventually consistent |
| storage system. Eventually consistent implies that all updates reach all |
| replicas eventually. Divergent versions of the same data may exist |
| temporarily but they are eventually reconciled to a consistent state. |
| Eventual consistency is a tradeoff to achieve high availability and it |
| involves some read and write latencies.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="lightweight-transactions-with-linearizable-consistency"><a class="anchor" href="#lightweight-transactions-with-linearizable-consistency"></a>Lightweight transactions with linearizable consistency</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>Data must be read and written in a sequential order. Paxos consensus |
| protocol is used to implement lightweight transactions. Paxos protocol |
| implements lightweight transactions that are able to handle concurrent |
| operations using linearizable consistency. Linearizable consistency is |
| sequential consistency with real-time constraints and it ensures |
| transaction isolation with compare and set (CAS) transaction. With CAS |
| replica data is compared and data that is found to be out of date is set |
| to the most consistent value. Reads with linearizable consistency allow |
| reading the current state of the data, which may possibly be |
| uncommitted, without making a new addition or update.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="batched-writes"><a class="anchor" href="#batched-writes"></a>Batched Writes</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>The guarantee for batched writes across multiple tables is that they |
| will eventually succeed, or none will. Batch data is first written to |
| batchlog system data, and when the batch data has been successfully |
| stored in the cluster the batchlog data is removed. The batch is |
| replicated to another node to ensure the full batch completes in the |
| event the coordinator node fails.</p> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="secondary-indexes"><a class="anchor" href="#secondary-indexes"></a>Secondary Indexes</h2> |
| <div class="sectionbody"> |
| <div class="paragraph"> |
| <p>A secondary index is an index on a column and is used to query a table |
| that is normally not queryable. Secondary indexes when built are |
| guaranteed to be consistent with their local replicas.</p> |
| </div> |
| </div> |
| </div> |
| </article> |
| </main> |
| </div> |
| </div> |
| <footer class="grad grad--two flex-center pb-xlarge"> |
| <div class="inner text-center z2 relative"> |
| <h2 class="white py-small">Get started with Cassandra, fast.</h2> |
| <a id="footer-cta" href="/_/quickstart.html" class="btn btn--filled ma-medium">Quickstart Guide</a> |
| </div> |
| <div class="inner flex flex-distribute-items mt-xlarge z2 relative"> |
| <div class="col-2"> |
| <div id="footer-logo" class="logo logo--footer mb-medium"><img src="../../../../assets/img/logo-white-r.png" alt="Cassandra Logo"></div> |
| <p>Apache Cassandra<img src="../../../../assets/img/registered.svg" alt="®" style="width:18px;"> powers mission-critical deployments with improved performance and unparalleled levels of scale in the cloud.</p> |
| <div class="footer-social-icons"> |
| <a href="https://twitter.com/cassandra?lang=en" target="_blank"><img src="../../../../assets/img/twitter-icon-circle-white.svg" alt="twitter icon" width="24"></a> |
| <a href="https://www.linkedin.com/company/apache-cassandra/" target="_blank"><img src="../../../../assets/img/LI-In-Bug.png" alt="linked-in icon" width="24"></a> |
| <a href="https://www.youtube.com/c/PlanetCassandra" target="_blank"><img src="../../../../assets/img/youtube-icon.png" alt="youtube icon" width="24"></a> |
| </div> |
| </div> |
| <div class="col-2 flex flex-center"> |
| <ul class="columns-2"> |
| <li class="mb-small"><a href="/">Home</a></li> |
| <li class="mb-small"><a href="/_/cassandra-basics.html">Cassandra Basics</a></li> |
| <li class="mb-small"><a href="/_/quickstart.html">Quickstart</a></li> |
| <li class="mb-small"><a href="/_/ecosystem.html">Ecosystem</a></li> |
| <li class="mb-small"><a href="/doc/latest/">Documentation</a></li> |
| <li class="mb-small"><a href="/_/community.html">Community</a></li> |
| <li class="mb-small"><a href="/_/case-studies.html">Case Studies</a></li> |
| <li class="mb-small"><a href="/_/resources.html">Resources</a></li> |
| <li class="mb-small"><a href="/_/blog.html">Blog</a></li> |
| </ul> |
| </div> |
| </div> |
| </footer> |
| <div class="lower-footer bg-white pa-medium"> |
| <div class="flex flex-row flex-vert-center"> |
| <div class="pr-medium"><img src="../../../../assets/img//feather-small.png" alt="ASF" width="20"></div> |
| <div class="pr-medium"><a href="http://www.apache.org/" target="_blank">Foundation</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/events/current-event.html" target="_blank">Events</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/licenses/" target="_blank">License</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/foundation/thanks" target="_blank">Thanks</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/security" target="_blank">Security</a></div> |
| <div class="pr-medium"><a href="https://privacy.apache.org/policies/privacy-policy-public.html" target="_blank">Privacy</a></div> |
| <div class="pr-medium"><a href="https://www.apache.org/foundation/sponsorship" target="_blank">Sponsorship</a></div> |
| </div> |
| <p class="my-medium">© 2009-<script>document.write(new Date().getFullYear())</script> <a href="https://apache.org" target="_blank">The Apache Software Foundation</a> under the terms of the Apache License 2.0. Apache, the Apache feather logo, Apache Cassandra, Cassandra, and the Cassandra logo, are either registered trademarks or trademarks of The Apache Software Foundation.</p> |
| </div> |
| <div id="fade" class="hidden"></div> |
| <div id="modal" class="hidden"> |
| <div id="close-modal" class="cursor-pointer"><svg viewBox="0 0 24 24" width="24" height="24" stroke="currentColor" stroke-width="2" fill="none" stroke-linecap="round" stroke-linejoin="round" class="css-i6dzq1"><line x1="18" y1="6" x2="6" y2="18"></line><line x1="6" y1="6" x2="18" y2="18"></line></svg></div> |
| <div id="mod-content" class="vid-mod-content resp-container"></div> |
| </div> |
| <script src="../../../../assets/js/site.js"></script> |
| <script async src="../../../../assets/js/vendor/highlight.js"></script> |
| <script src="../../../../assets/js/vendor/lunr.js"></script> |
| <script src="../../../../assets/js/vendor/search.js" id="search-script" data-base-path="../../../.." data-page-path="/Cassandra/4.0/cassandra/architecture/guarantees.html"></script> |
| <script async src="../../../../assets/../search-index.js"></script> |
| <script> |
| jQuery(function(){ |
| var windowW = $(window).width(); |
| $(document) |
| .on('click','.mobile-nav-icon',function(){ |
| $('.main-nav').fadeIn(); |
| }) |
| .on('click','.main-nav',function(){ |
| if(windowW <= 1000){ |
| $(this).fadeOut(); |
| } |
| }) |
| .on('click','#version-toggle',function(){ |
| $(this).toggleClass('active'); |
| $(this).next().fadeToggle(); |
| }) |
| .on('click','#mobile-docs-nav-burger', function(){ |
| $(this).toggleClass('active'); |
| $('.docs-nav').toggleClass('active'); |
| }); |
| var url = window.location.pathname; |
| var isQuickstart = url.includes('quickstart.html'); |
| if(isQuickstart){ |
| var footerCTA = document.getElementById('footer-cta'); |
| footerCTA.innerHTML = 'Get latest updates'; |
| footerCTA.setAttribute('href', '/_/blog.html'); |
| } |
| }); |
| </script> |
| </div> |
| </body> |
| </html> |
